Archie J P, Feldtman R W
Wake Medical Center, Raleigh, North Carolina 27609.
J Surg Res. 1989 Mar;46(3):253-5. doi: 10.1016/0022-4804(89)90066-8.
Phenylephrine is frequently used to increase systemic arterial pressure during carotid endarterectomy. However, little is known of its effect on collateral cerebral perfusion pressure, particularly in patients with high collateral cerebral vascular resistance who are at increased risk of cerebral ischemia during carotid clamping. We tested the hypothesis that this subset of patients can have collateral perfusion pressure, and hence collateral cerebral blood flow, increased in a predictable way by elevating systemic arterial pressure. We measured mean systemic arterial pressure (Pa), jugular venous pressure (Pv), and mean carotid back pressure (Pc), and calculated collateral cerebral perfusion pressure (P = Pc - Pv) and the ratio of collateral to ipsilateral hemisphere cerebral vascular resistance (Rc/Rh) in 18 patients with low P. Initial measurements were Pa = 84 +/- 8.8 (mm Hg, mean +/- SD), Pv = 7.8 +/- 3.9, Pc = 26 +/- 5.1, P = 18 +/- 4.5 and Rc/Rh = 3.4 +/- 1.15. During phenylephrine infusion, Pa = 108 +/- 11, Pc = 32 +/- 6.5, and P = 24 +/- 7.2, increases of 29, 23, and 33%, respectively (P less than 0.05). Unchanged were Pv = 8.2 +/- 4.1 (5%) and Rc/Rh = 3.5 +/- 1.30 (3%) (P greater than 0.8). The latter two findings indicate that cerebral perfusion pressure and mean systemic arterial pressure are linearly related according to the fluid mechanics equation governing these parameters: Pa = P(Rc/Rh + 1) + Pv. These results support the use of phenylephrine to increase collateral blood flow during carotid endarterectomy in patients with low cerebral perfusion pressure.
去氧肾上腺素常用于颈动脉内膜切除术期间提高体循环动脉压。然而，其对侧支脑灌注压的影响却鲜为人知，尤其是在那些侧支脑血管阻力高、颈动脉夹闭期间发生脑缺血风险增加的患者中。我们检验了这样一个假设，即通过升高体循环动脉压，这一亚组患者的侧支灌注压以及侧支脑血流量能够以可预测的方式增加。我们测量了18例低灌注患者的平均体循环动脉压（Pa）、颈静脉压（Pv）和平均颈动脉背压（Pc），并计算了侧支脑灌注压（P = Pc - Pv）以及侧支与同侧半球脑血管阻力之比（Rc/Rh）。初始测量值为：Pa = 84 ± 8.8（毫米汞柱，均值 ± 标准差），Pv = 7.8 ± 3.9，Pc = 26 ± 5.1，P = 18 ± 4.5，Rc/Rh = 3.4 ± 1.15。在输注去氧肾上腺素期间，Pa = 108 ± 11，Pc = 32 ± 6.5，P = 24 ± 7.2，分别升高了29%、23%和33%（P < 0.05）。Pv = 8.2 ± 4.1（升高5%）和Rc/Rh = 3.5 ± 1.30（升高3%）未发生变化（P > 0.8）。后两项结果表明，根据控制这些参数的流体力学方程，脑灌注压与平均体循环动脉压呈线性关系：Pa = P(Rc/Rh + 1) + Pv。这些结果支持在脑灌注压低的患者进行颈动脉内膜切除术期间使用去氧肾上腺素来增加侧支血流量。
